1. Field of the Invention
The present invention relates to a new and improved method and apparatus for the gasification of the organics contained in ashes, such as produced in hog-fuel fired boilers, and vitrification of the inorganics left after gasification.
2. Brief Description of the Prior Art
Methods and apparatus have been proposed to more efficiently burn all the available fuel in waste products, such as wood scraps, bark, shavings, plywood trim, and rejects. The objectives are both to maximize the amount of combustion heat and to minimize the volume of the ash produced. Apparatus and methods have also been proposed for reburning ash material of a previously burned primary fuel. The extent of the ash problem is well illustrated by the fact that, for example, in Canada approximately 1000 tonnes of ashes are produced every day from the sole burning of bark.
Thus, in U.S. Pat. No. 5,161,471, the reburning apparatus has been adapted to work in parallel with the primary combustion unit. In this case, combustion air is introduced over the whole floor area of an ash reburn vessel. The reburned ash is then disposed of without further treatment.
By contrast, in U.S. Pat. No. 4,960,380, there is disclosed a method and an apparatus for the reduction of solid waste material, wherein a powerful laser is used to produce a plasma in which the solid waste materials are reduced to a slag-like material. In this case, however, the treatment is not adapted to work in parallel with the primary combustion unit and the energy is not recovered, the objective being solely to produce a slag.
In Canadian Patent Application No. 2,106,746, a melting furnace is disclosed for the treatment of the combustion ash resulting from incineration of municipal and other sorts of waste by melting the ash and utilizing the unburnt carbon contained in the ash itself as the main source of heat. This combustion is assisted by a plasma torch which uses air as its working gas. The treatment of the ash is made in line with the primary combustion unit of the waste.